The field of this invention is actuator control systems and the like.
Valve actuator control systems are frequently employed with fluid handling networks to control the operation of actuators which open and close valves in the network.
So far as is known, actuator control systems typically included a supply line to supply operating fluid or power and one or more signal lines separate and apart from the supply line to convey control pressure or signals. Upon receipt of the control signals, a valve in the control system directed fluid from the supply line to the actuator to move the actuator.
These are disadvantages to these control systems. One such disadvantage was that the supply line had to be large enough to supply sufficient quantities of operating fluid at a rate to achieve the desired speed of operation of the actuator. Providing these large supply lines increased the cost of the control system. Further, in some of these systems, if the supply line was broken or otherwise failed, the control systems were without fluid to operate the actuator. Also, if the signal line was broken or otherwise failed, there was no way to transfer control signals to the actuator to ensure that the valve operated by the actuator was in the proper position.